Circuit-interrupter.



Witnesses:

C. LICHTENBERG. CIRCUIT INTERRUPTER. APPLICATION FILED ocT. II. I9I2.

1&375340. Patented Apr. 27,1915.

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UNITED STATES PATENT OFFICE.

CHESTER LICHTENBERG, 0F SCHENECTADY, NEW YORK, ASSIGNOB TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CIBCUIT-INTERRUPTER.

Specication of Letters Patent.

Application led October 11, 1912. Serial No. 725,176.

To all whom t may concern:

Bel it known that I, CHESTER LICHTEN- nunc, a citizenof the United States, residing at Schenectady,- county of Schenectady, State -of New York, have invented certain new and useful Improvements in Circuit- Interrupters, of Vwhich'the following is a specification.

My invention relates to devices for interrupting electric circuits, and more particularly'tooil circuit'interrupters of the type in which there is an air space of greater or less volume aboveI the surface ofthe oil.

I have found that'in anl oil circuit interrupter having an 'air space above the oil,. the air in the air space mixes with oil vapor and forms an iniammable mixture. Under certain conditions the proportion of air and oil 'vapor may be such that the mixture is explosive.; I have, furthermore, found that much O' he'destructive eects sometimes observed when oil circuit interrupters of this type are opened under extremely severe conditions, areduevto the ignition of this mixture of oil vapor and'air'at the surface of the oil, rather than to any direct explosive action of the are, In many cases the circuit has been opened and-the arc' practically extinguished l fore the destructive explosion and rush of fire! from the -circuit interrupter occurs.

Thel objject ofv my invention is to prevent ignitiengof-the' inflammable mixture in the air space above the oil.

'To this end I provide some suitable means which will permit the vapors generated by the arc in the body of the oil to escape freely from the oil, but which will insure that none o f the hot vapors or heated particles given pif-'by the 'arc can reach the air space above thearc until'they are cooled so much that they cannot 'ignite an explosive or infiammable mixture in the air space.

For a better understanding of my invention, 'reference may be had to the accompanying drawing, in which, merely for pur-- poses of illustration, I havel shown one of the variousvformsin which my invention may be embodied, and in which- Figure 1 is a longitudinal section of one form of circuit interrupter embodying my invention; Fig. 2 is a transverse section of the circuit interrupter shown in Fig. 1; Fig. 3 is a longitudinal section of a circuit interruptor in which my invention is embodied in a slightly modied form; and Fig. 4 is a horizontal section along the line 4-4 of Fig'. 3 showing details of construction.

In the particular form of circuit interrupter which I have chosen to illustratemy invention, an oil tank 1V is a partially filled.

with oil or yother suitable insulating iiuid.

My invention is applicable to any circuit interrupter having an insulating fluid which, under the iniiuence of the arc or in any other way, will produce an iniammable or explo.- sive mixturein the air space above the inslulating fluid. but oil isthe insulating fluid most commonly used in circuit interrupters of this type. The oil tank 1 is provided with a cover 2 which lits the oil tank quite closely and leaves between the cover and the surface of the oil an air space which may be of greater or less volume, depending upon the size of the circuit interrupter. The cover 2 supports insulators 3 on the lower ends of which are mounted iixed contacts 4 submerged in the oil in the oil tank.' When the circuit is to be closed, the fixed contacts 4 are connected by a bridging contact 5 mounted upon the lower end4 of a vertically movable operating rod 6, which may be raised and lowered by some suitable actuating mechanism, not shown. When the circuit is to be opened, the bridging contact 5 drops away from the stationary contacts 4 into the posi'- tion shown in Fig. 1. As the contacts separate, arcs are formed which produce -a very high temperature and result in the formation of very hot bubbles of oil vapors and glowing particles of metal` These arcs are" eventually extinguished bythe oil.

In order to guard against ignition of any inammable or explosive mixture in the air space above the oil, I mount asuitable barrier or screen above the point of separation of the contacts and between the contacts and the surface of the oil, so that hot gases and' particles cannot reach the air space above the oil except by passing through the barrier or screen. This barrier or screen may4k be made in many di'erent forms as long as it is so constructed that hot gases and p'articles passing through it must Abe cooled to the desired extent before they can escape into the air space above the oil. The preferred form of barrier, as shown in the drawing, is inade in the form of a grid consisting of a plurality of plates 7, mounted side by side and insulated from one another, these plates being strung along on suitable supports 8 which extend across the oil tank and are supported in any suitable way, as by the walls of the oil tank. The plates 7 are made of some good heat conducting material., preferably metal. The spacing of the plates with relaj tion to one another is such that gases can pass from the neighborhood of the arc through the barrier and into the air space above the oil, but will necessarily be in such intimate contact with the plates while passing between them that .the gases aie cooled to a temperature considerably below that required to ignite any inflammable or eXplosive mixture which maybe present in any oil space above the oil.

The grid or barrier may be located iii any position which will enable it to intercept all the hot gases before they pass into the air space above the oil, but in the preferred construction it is located just below the surface of the oil, as shown in the drawing. By this construction, the plates 7 are always submerged in the oil, remain at the temperature of the oil, and offer considerable resistance to a sudden upward rush of gases, owing to the viscosity of the oil and the adhesion of the oil to the plates. There is no danger that the barrier, even when constructed of metal plates, will act as a bridge to permit the are to extend from one fixed contact to the other. such an arc could not exist, as it would be divided up into 'a large number of short arcs inseries, exposed both to the cooling action of the plates 7 and also tc: the extinguishing action of the oil. j

n the particular arrangement shown in Fig. 1, the plates 7 with their upper edges at the same level, are disposed transversely of the oil tank. The 'plates adjacent to the insulators 3 are the narrowest, the others gradually increasing in width toward the operating rod 6 and toward the sides of the oil tank. As a result of this construction, the lower edges of the plates form a s'ort of `bell or inverted funnel which catches all the are gases and compels them to pass through the plates on their way to the air space above the oil.

In the modiication shown in Figs. 3 and 4, the barrier or grid is made up of a number of concentric heat conducting plates 9 mounted around each insulator and held in place by suitable supports 10. The plates operate in the saine way as the plates 7 and The plates 7 are insulated, and.

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are so mounted that their lower edges form a bell or inverted funnel for catching all of the oil bubbles and particles which are given olf by the are and which tend to rise through the oil into the air space above the oil.

As in the arrangement shown in Fig. 1, the plates 9 are so spaced that the gases can pass between them with comparatively little resistance, but lnevertheless are so cooled during their passage that there is no danger of ignition of inflammable or explosive mixtures in the air space above the oil.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. A circuit interrupter comprising a vessel containing insulating liquid, a cooling barrier mounted just below and near the sur face of liquid having a plurality of permanently opened constricted passages for the escape of ases from said liquid, and relatively mova le coperating contacts submerged. in the liquid in said vessel and separable to draw an arc beneath said cooling barrier.

2. A circuit interrupter comprising a vessel partially iilled with oil, relatively movable coperating contacts separablein said vessel beneath the surface of the oil, and cooling means mounted just below and near the surface of the oil for cooling the products of the arc before said products reach the surface of the oil.

3. A circuit interrupter comprising a vessel partially filled with oil, relatively movable`contacts mountedto separate in said vessel beneath the surface of the oil, and a pluralityof cooling members spaced apart and mounted just below and near the surface of the oil Afor reducing the temperature of the arc gases before they reach the air space above the oil.

4. A circuit interrupter comprising a vessel containing insulating liquid, relatively movable coperating contacts separable to draw an arc in said liquid, and a metal cooling screen comprising a plurality of plates so mounted just below and near the surface of the oil as to formfor the hot arc gases submerged vents which cool to a safe temperature the gases passing through it.

5. A circuit interrupter comprising a vessel partially illed with oil, relatively movable contacts mounted to separate in said vessel beneath'the surface of the oil, and a cooling grid mounted just below and near the surface of the oil comprising a plurality of permanently opened constricted passages interposed in the path of `hot gases to cool said gases before they reach the air space above the oil.

movable coperating contacts separable to draw an are in said liquid, and a plurality of plates concentrically arranged just below l12b 6. A circuit interrupter comprising a ves-x sel containing insulating liquid, relatively.

` able contacts mounted to separate in said vvessel beneath the surface of the oil, and a Witnesses:

and near the surface of the liquid to form a. and near the surface of the oil to form a. 10 cooling screen between the arc and the surscreen through which gases generated by the face of said liquid. are must pass to reach the surface of the oil.

7. A circuit interrupter comprising a ves- In witness whereof, I have hereunto set sel partially filled with oil, relatively movmy hand this 7th day of September 1912.

CHESTER LICHTENBERG.

plurality of plates insulated from one an- BENJAMIN B. HULL, other and concentrically arranged just below `HELEN ORFORD.

Gopies of this patent may be obtained for five 'cents each, by addressing the Commissioner of Patents, Washington, D. C. v 

